The National Education Association, the largest teachers union, yesterday called for an almost complete ban on school districts hiring teachers who lack full credentials.

In the face of teacher shortages, many urban districts have resorted to issuing more emergency, temporary or alternative teaching certificates to college graduates who have not completed the required education course work or passed a state licensing exam. School officials in California and elsewhere also have bypassed normal rules in hiring additional teachers to reduce class sizes.

Bob Chase, president of the National Education Association, said the nation has more than enough people who are fully qualified to teach, but many have abandoned the profession because of salaries that average $35,000 nationally. He predicted that insisting on the required credentials would create market pressures to raise salaries and would also put better teachers in the classroom, helping lift student achievement.

"Let's have a fully prepared, qualified teacher in every classroom. No waivers. No exceptions. No excuses," Chase said at a news conference.

Later, in response to questions, Chase did leave open one exception: New teachers who agree to intense supervision and mentoring with a proviso they meet state standards for certification within a few years.

Michael Casserly, executive director of the Council of Great City Schools, said he agreed with Chase's goal in the long run but added that the large urban districts he represents issue emergency certificates as a practical response to shortages.

"The day before school opens, principals face this option: Start those classes with nobody, or somebody who can fill part of the void," Casserly said.

Arthur Wise, president of the National Council for Accreditation of Teacher Education, joined Chase at the conference and endorsed his call for changes in hiring practices. Wise went as far as to suggest that anyone lacking full credentials should not even be called a teacher--but instead an "instructor."

Chase also proposed adding what in most states would be a new requirement for certified teachers--graduation from a teacher training program accredited by Wise's organization, the principal accrediter of schools of education. About 500 of the nation's 1,300 teacher-training programs are accredited.